Punch



(No Model.)

' G. B. TENNANT.

I PUNCH. No. 434,738. Patented Aug. 19, 1890.

WITNESSES INVENTOR UNITED STATES PATENT. OFFICE.

GEORGE B. TENNANT, OF UNIONTOWN, PENNSYLVANIA.

PUNCH.

SPECIFICATION forming part of Letters Patent No. 434,738, dated August19, 1890. Application filed November 23, 1889. Renewed July 24, 1890.Serial No. 359,733. (No model.)

To aZZ whom it may concern.-

Be it known that I, GEORGE E. TENNANT, of Uniontown, in the county ofFayette and State of Pennsylvania, have invented a new and usefulImprovement in Punches, of which the following is a full, clear, andexact description, reference being had to the accompanying drawing,forming part of this specification, which is aside elcvation,partly insection, of my improved punch set in the holder.

The object of my invention is to improve the construction of punchessuch as are commonly used for punching metal by enabling the punches tobe used for a longer time than has heretofore been possible. Punches ofthis class are composed of bars of steel, generally about six or eightinches long, adapted to be set in a holder at the end of thereciprocating plunger. The end of the bar is made of proper size andshape to do the work of punching, and by reason of the severe nature ofsuch work the end of the punch soon wears out or breaks, and as thisoccurs it has heretofore been necessary to discard the punch as uselessand to replace it in the holder with a new one. This is entirelyprevented by my invention, which enables the punch, when worn, to bedressed and reshaped and to be used until nearly its entire length byrepeated wear and reshaping has been reduced.

Referring to the drawing, 2 represents the punch-holder having the usualpunch-cavity.

3 is the punch, which may be made of the usual shape, except that at therear end it is provided with a screw-threaded socket for the receptionof a screw-plug, hereinafter described. When the end of the punch wearsout or breaks, it is dressed and turned again into proper shape, and tocompensate for the reduction in length I attach to it a packingpiece 4,which is of the same cross-section as the punch, so as to be capable offitting neatly in the holder, and which is of such length that, togetherwith the remaining part of the punch, it shallbe of the original lengthof the latter. I prefer to secure this packingpiece to the punch bymeans of a screw-plug 6, which is fitted in the threaded socket in theend of the punch and in a correspondinglythreaded socket in thepacking-piece. The punch and packing-piece thus united are placed in thecavity of the holder, and are therein confined by means of the usualsetscrews 5. At each redressing of the punch the packing-piece may bereplaced by one somewhat longer, so that the total length of theconjoined punch and packing-piece shall be constant, and thatthe rearend of the latter may have a solid bearing at the end of theholder-cavity, though within certain limits the same end may be obtainedby interposing small blocks between the end of the packing-piece and theend of the cavity. The punch may thus continue to be used for aconsiderable time after it has so worn that the set-screw shall nolonger engage the punch proper, but the packing-piece back of the punch.WVhen the punch is thus held, the

screw connection between the packing-piece and punch is suificient tostrip the punch from the metal on the back-stroke of themachine-plunger.

Other modifications in form and construction of my improvement may bemade bythe skilled mechanic without departing from the principles of myinvention.

What I claim is 1. The combination,with the punch, of a packing-pieceremovably secured to the end thereof, substantially as and for thepurposes described.

2. The combination, with the punch, of a packing-piece removably securedto the end thereof by a screw-plug, substantially as and for thepurposes described.

In testimony whereof I have hereunto set my hand this 6th day ofNovember, A. D. 1889.

GEORGE B. TENNANT.

